From the past, whether natural or synthetic, leathers are widely used in many applications including car seats, furniture, clothing, shoes, bags, sanitary products, and outdoor tents. For use in these applications, leather must have abrasion resistance and slippage while a satisfactory countermeasure against staining must also be taken therefor. Most of prior art resin compositions for use with leather are of solvent type, i.e., using organic solvents for improving film-forming properties. In consideration of their impacts to the human body and environment, efforts are made to develop aqueous resin compositions.
One known method for improving the abrasion resistance and slippage of leather is to incorporate a silicone component such as silicone oil or silicone powder in a resin composition from which leather is prepared. For example, Patent Document 1 discloses the preparation of a synthetic leather including an elastomer layer having acrylic-silicone copolymer particles kneaded in a urethane elastomer. Although abrasion resistance is improved, kneading of particles in resin complicates the overall process. The amount of acrylic-silicone copolymer particles loaded must be increased to acquire a certain level of abrasion resistance.
This problem may be solved by coating the surface of natural or synthetic leather with resins or the like. Patent Document 2 discloses a surface finish composition comprising an aqueous polyurethane resin, a crosslinker and a polyether-modified silicone, with which synthetic leather is coated for improving abrasion resistance. However, since this surface finish composition is highly hydrophilic, the lack of anti-staining at the leather surface becomes a concern. For example, when deep colored beverage or liquid such as coffee deposits on the leather, the liquid color is transferred to the leather. When the leather is rubbed with clothing, the color of fibers is transferred to the leather.
It is also known that the anti-staining property of leather is improved by coating the leather surface with resins or the like. Patent Document 3 discloses that natural leather is coated with a topcoat composition comprising an acrylic resin, an acrylic-silica resin, an acrylic-polysiloxane resin, a silicone base touch-improver and other components. Patent Document 4 describes synthetic leather made of urethane resin which is surface coated with a silicone resin coating. These coatings are still unsatisfactory as the aqueous-based coating meeting both abrasion resistance and anti-staining properties, leaving room for improvement.